This gif animation compares two luminance frames of LBN 7 with an exposure time of 6min, which were captured on two consecutive nights at the same altitude of 45°. Both nights were completely cloudless, but in the second night Calima (a hot, sand laden wind that blows in from the Northern Sahara) worsened the transparency.Image acquisition by CEDIC team (Bernhard Hubl, Christoph Kaltseis, Markus Blauensteiner, Michael Hanl)Image processing by Bernhard Hubl